Device for manufacturing semi-finished products and molded articles of a metallic material

ABSTRACT

The apparatus is described for manufacturing semi-finished products and molded articles of metallic materials. The device incorporates an extruder for producing a flow of the metals, with appliances being connected thereafter for shaping the semi-finished products and the molded articles. The extruder has a screw system consisting of two or more meshing screws. This design has an improved functionality and can produce components with reproducible quality.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of PCT Application No.PCT/EP00/01417, filed Feb. 21, 2000, which claims the priority of Germanpatent application DE 199 07 118.7 filed Feb. 19, 1999.

FIELD OF THE INVENTION

[0002] The invention relates to a device for manufacturing semi-finishedproducts and molded articles of metallic material incorporating anextruder for producing a metal flow and appliances connected thereafterfor molding the semi-finished products and the molded articles.

BACKGROUND OF THE INVENTION

[0003] A device of this type for die-casting preforms is known from EP 0080 787, wherein a metallic material having dendritic properties, amagnesium alloy for example, is converted into a thixotropic state in anextruder. In this state, the metallic material has a mud-like or pastyconsistency and can be processed so as to form metallic molded articlesin the molding appliances following the extruder.

[0004] From EP 0 080 787, it is known to use a die-casting unitconnected after the extruder for the molding or shaping operations, orelse to process this material directly in a conventional injectionmolding machine without previously processing the metallic material inan extruder. There however, processing in an injection molding machineis disregarded because of the superimposition of rotational andtranslational movements by the injection worm (reciprocating screw) andthe increased problems of sealing arising thereby in comparison with theuse of the extruder (merely rotational).

[0005] The process of converting the metallic material (e.g. themagnesium alloy) into a thixotropic mass in the extruder is effected, inthe manner described in EP 0 080 787, by feeding the material ingranular form into a pre-heated feed hopper, whereby the size of thegranular particles is made such that they can be easily processed by thescrew in the extruder. The heating of the granules is effected at atemperature which is close to or above the solidus temperature wherebythe heating process may take place either prior to and/or in theextruder.

[0006] The metallic material is in any case subjected to further heatingin the extruder by means of external heating devices that are effectivevia the screw cylinder, and also as a result of frictional heat (shearstress). Hereby, the heating process in the extruder is controlled insuch a manner that the temperature of the metallic material will remainbelow its liquidus temperature.

[0007] Due to the maintenance of a temperature in the range between thesolidus and the liquidus temperatures and also due to the shear stress,the effect achieved in the extruder is that the dendritic structures ofthe metallic material will be broken down and a solid-liquid metal alloyin a thixotropic state will emerge from the output of the extruder.

[0008] In this device for producing a solid-liquid thixotropic metalalloy which is known from EP 0 080 787, there is a feed channel in theform of a continuous helical channel between the flanks of the screwfrom the start of the screw up to the end thereof.

[0009] Basically, the underlying principle of the conveying process inan extruder is that the material being moved experiences frictionagainst the cylinder walling of the extruder and glides over theso-called base of the screw. When processing metallic materials, theproblem arising as a result of the high thermal conductivity is thatthere is a build up of a smelt film on the cylinder walling, said filmbeing of very low viscosity and considerably reducing the frictionbetween the material being moved and the cylinder walling therebyleading to a drastic reduction in the performance of the conveyingprocess. Moreover, the mixing process also suffers to a considerableextent whereby a growing temperature gradient over the cross-section ofthe interior of the extrusion cylinder, which gradient increases fromthe exterior to the interior thereof, cannot be effectively dissipated.

[0010] As a consequence of these conditions, there arise inhomogeneitiesbetween the solid and liquid components and the stability of theconveying process becomes extremely unsatisfactory whilst the build upof pressure is highly erratic. Continuously altering process statesthereby arise whereby the resultant non-reproducible quality of thecomponents has to be accepted.

[0011] It is therefore desirable to improve the construction andfunctionality of a device of the type mentioned in such a manner thatreproducible component-qualities can always be produced.

SUMMARY OF THE INVENTION

[0012] According to one aspect of the invention, an extruder forproducing a flow of metal and appliances connected thereafter forshaping the semi-finished products and the molded articles includes ascrew system consisting of two or more meshing screws.

[0013] In the case of the device in accordance with the invention, theprocessing of the metallic material, for example, starting from thegranular state up to the thixotropic solid-liquid material or the liquidmaterial states thereof, is effected in such a manner that, taken withreference to the axial length of the extruder, the processing steps willgenerally be consistent and the material will be continuously advanced.The negative consequences of fluctuations in temperature and theirregularities of viscosity inherent therein together with theproportional composition of the liquid material components are therebyreduced to a negligible amount.

[0014] It has been found that the previously described problemencountered in single screw extruders can be eliminated by means of anextruder including a screw system comprising two or more meshing screws,although the problems described above still have to be taken intoaccount initially even with this type of extruder. Here however, thereis a counteracting mechanism at work which, surprisingly, is ofsufficient extent as to allow the material being conveyed to betransferred from one screw onto the adjacent meshing screw. It isevident thereby, that when processing metallic materials, an adequatelylarge mixing and transportation effect is achieved which ensurescontinuous advancement of the metallic material being conveyed inaddition to the dissipation of the temperature gradient. Stable feedingof fresh material into the inlet zone of the extruder has also beenobserved in addition to the increase in mixing performance.

[0015] This has a particularly positive effect when processing materialsin granular or chip-like form since the bulk density thereof oftypically approximately 0.5 to 0.8 g/cm³ has to be doubled or brought upto the still higher densities of approximately 1.7 g/cm³ or more of thesolid-liquid stream of material. This is difficult if not impossible inthe case of the reduced conveyor performance of an extruder.

[0016] Heating strips or heating devices functioning inductively areused conventionally for the purposes of introducing heat when processingmetallic smelts.

[0017] However, inductive heating devices are very expensive. Classicalheating strips are mounted around the periphery of the extruder cylinderengine and tend to become heavily oxidized at the high temperaturesprevailing when processing metallic smelts, this leading to scaling ofthe cylinder surface and hence reducing thermal transfer between theheating body and the cylinder. Moreover, precautions have to be takenwhen using heating strips so as to retain them in continuous contactwith the surface of the cylinder in order to achieve adequate thermaltransfer.

[0018] Another disadvantage associated with heating strips is the largespacing between the heating strips mounted externally on the extrudercylinder and the smelt present in the interior of the cylinder in theface of the necessarily high heat flow densities and temperaturegradients of up to 200° C. and more which occur in operation.

[0019] If the ratios involved even in the case of a single screwextruder are not particularly favorable, then the heat introductionratio is still less favorable in the case of two and more screwextruders since the spacing between the outer cylinder surface and theinner walls thereof is inevitably increased here due to the geometricalconsiderations.

[0020] In accordance with the invention, so-called heating cartridges,which comprise resistance heating elements arranged in a usuallycylindrical housing, are of assistance here.

[0021] The heating cartridges can be arranged in transverse bores in thecover of the extruder cylinder very close to the inner walling of thecylinder, for example, above and below the double cylinder chamber inthe two screw extruder. The transverse bores themselves may behermetically sealed using an airtight and heat resistant material sothat they will be protected from scaling.

[0022] Substantially greater heat flow densities can be obtained due tothe very small spacing between the heating cartridges and the innerwalling of the extruder cylinder. Moreover, the outer surface of theextruder cylinder can be insulated to a still greater extent againstloss of heat by the use of the heating cartridges arranged in thecylinder walls.

[0023] The extruder together with the heating cartridges mounted thereincan be produced in such a manner that the tie rods thereof are arrangedoutside the insulating means and thus located in a considerably coolerregion. Substantially more economical materials can thereby be usedtherefor.

[0024] The driving arrangement for the extruder screws as well as thedriving arrangement for the die-casting pistons is often implemented bymeans of hydraulic systems.

[0025] However, there is a certain safety risk in regard to thecombustibility of the hydraulic fluids due to the high temperaturesoccurring when processing metal smelts.

[0026] Accordingly, electrical drives are preferably used for thescrews, but so too, electrical drives could also be used for driving thedie-casting pistons rather than a hydraulic system.

[0027] Granular materials having dissimilar shaped grains can now beprocessed by means of the method in accordance with the invention andthus, in toto, there is a considerably broader spectrum of startingmaterials available, whereby one can resort to more economical startingmaterials.

[0028] Furthermore, due to the continuous conveying process, the bandwidth of the period in which the materials being conveyed will remain inthe extruder is reduced, this being shown by a uniform grain size in theglobulites in the structure of the finished preforms or semi-finishedproducts.

[0029] The previously described effects are immediately apparent if thescrews rotate in the same sense. The positive effect is strengthened byusing closely engaging screws.

[0030] Alternatively, screws rotating in the opposite sense could alsobe used, whereby an enforced advancement process would then beimplemented here.

[0031] The extruder may be followed by one or more die-casting mouldswhich are adapted to be loaded with metallic material on a continuous ordiscontinuous basis via multi-way switches and heated channels.

[0032] A reduction of the production cycle can thereby be implemented,or larger components, especially thin-walled large surface areacomponents can be manufactured, whereby a plurality of die-casting unitscan be connected to a molding cavity.

[0033] Due to the controllable processing states that are always runninguniformly in the extruder, it is particularly suited for side feeding ofdiffering metallic and non-metallic materials, especially of reinforcingcomponents such as fibers for example.

[0034] Side feeding may be effected by means of a volumetric orgravimetric metering system.

[0035] Side feeding of the differing materials is effected at thosefunctional and temperature zones which are appropriate for therespective materials. Pure metals e.g. Li, Mg, Ca, Al, Si, Zn, Mn, rareearth metals and the like can thus be compounded to form metal alloys,and, by the same token, pre-existing alloys such as e.g. AlZn can besupplied to the extruder in accordance with the invention. Moreover,non-metallic materials such as e.g. reinforcing materials, fillers,seeding agents, catalysts and the like can also be worked into thesolid-liquid or liquid metal flow in this manner, whereby the extruderin accordance with the invention fulfils the function of a machine formanufacturing alloys or compound materials.

[0036] In addition, pre-prepared and especially liquid materials canalso be supplied via side feeding by the previously proposed aggregatessuch as the extruders for example.

[0037] Basically, components of constant quality are thereby producible,whereby they may consist of pure metal, metal alloys or of non-metallicmaterials mixed homogeneously with the metal or the metal alloys.

[0038] The appliances connected to the output of the extruder formolding the semi-finished products and preforms may be selected from alarge range. To mention just some of the most important:

[0039] Die-casting aggregates.

[0040] Continuous molding and extrusion aggregates.

[0041] In the case of die-casting aggregates, one should mention thosedie-casting aggregates that are equipped with a separate piston/cylinderunit such as are known from EP 0 080 787 for example.

[0042] Hereby, one should differentiate between the various types:

[0043] piston/cylinder aggregates which are filled at the front face ofthe piston, whereby the piston is in the withdrawn position at thebeginning of the filling operation in the case of one variant and thefilling operation takes place either directly in front of the piston orat a position displaced therefrom in the direction towards the cylinderopening; in an alternative variant, filling takes place at the cylinderopening and the piston is driven back or forced back during the fillingoperation, and in a further variant, the filling operation takes placein the cylinder chamber in front of the piston in the cylinder outletchannel and the piston is moved from the forward dead position by theinflowing metallic material into the withdrawn position.

[0044] In another embodiment, a so-called differential piston subdividesthe cylinder chamber of the die-casting cylinder into a feed chamberconnected via a heated channel to the extruder and an injection chamberconnected to the molding cavity. A fluidic connection is created betweenthe feed chamber and the injection chamber, said fluidic connectionincorporating a return-flow blocking device or a non-return valve whichcounteracts any return flow of metallic material from the injectionchamber into the feed chamber.

[0045] The differential piston has a greater area of piston surface atthe injection chamber side thereof and a smaller, usually annular pistonsurface at the feed chamber side thereof.

[0046] The thixotropic metallic material that it is fed by the extruderinto the feed chamber at a pressure of e.g. less than 120 bar is broughtup to the injection pressure of e.g. 500 bar or more, especially1000-2000 bar, by means of the differential piston, whereby losses dueto leakage play no part since the leaked quantities entering the feedchamber from the injection chamber will be fed back into the injectionchamber during the next injection phase.

[0047] Another advantage of the differential piston is that theproportionately low pressure in the material fed into the die-castingcylinder automatically returns the differential piston due to thepressure difference set up between the larger piston surface and thesmaller annular piston surface, whereby the insertion of multi-wayvalves between the extruder and the die-casting cylinder is therebyredundant. If necessary, this process can be assisted hydraulically.Finally, there also arises the advantage that the flow of metallicmaterial produced by the extruder is always advanced in just onedirection towards the injection process in the molding cavity, thisbeing particularly appropriate when processing materials into which longreinforcing fibers (e.g. carbon fibers) are to be worked and said fibersenter the extruder by side feeding.

[0048] Furthermore, the invention relates to a method of die-casting,continuous casting or extrusion molding metallic materials using anextruder followed by units for shaping semi-finished products andpreforms, especially of the typo described above. The use of an extruderincorporating a screw system comprising two or more meshing screwspermits the metallic material to be conveyed in the direction ofextrusion in a controlled manner. This also applies especially formaterials in the solid-liquid thixotropic state as well as for materialsin the liquid state.

[0049] Discontinuities occurring when processing the metallic materialare avoided by virtue of the controlled advancement process or theenforced advancement process, this making a considerable contribution toimproved consistency in the component quality of the metallic componentsproduced in the die-casting process.

[0050] The processing of the metallic material in accordance with theinvention and the controlled or enforced conveyance thereof in theextruder now permits, in a particularly simple and defined manner, theside feeding of further components, for example alloying components whenmanufacturing alloys, reinforcing components when manufacturing metalliccompound materials or other additional materials for modifying themetallic materials.

[0051] In particular, the controlled or enforced conveyance in theextruder ensures greater homogeneity of the metallic material produced.

[0052] In a series of cases, it is also useful to work at or above theliquidus temperature, especially in a range of approximately 5° C. to10° C. above liquidus.

[0053] Working above liquidus is to be recommended in some cases ofapplication since the mixing process is further assisted here and thisimproves especially the wetting of the added fibers.

[0054] An embodiment of the device in accordance with the invention willnow be described with reference to the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0055]FIG. 1 shows a schematic partially broken away illustration of adouble screw extruder in accordance with the invention;

[0056]FIG. 2 shows a schematic illustration of differing embodiments ofthe die-casting aggregates following the extruder in FIG. 1; and

[0057]FIG. 3 shows a sectional view through the extruder of FIG. 1 alongthe line III-III.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0058]FIG. 1 shows schematically an extruder 1 of the double screwextruder type, wherein two screws are mounted in the extruder cylinder 2thereof, only the front screw 3 being visible in the broken away regionillustrated The profile of the screw 3 engages in the profile of theneighboring screw located behind it. Thereby, the head face 4 of thescrew drive threads of the one screw 3 abuts the core face 5 of the (notvisible) neighboring screw. The spacing of the head diameter K₁ of theone screw relative to the core diameter K₂ of the neighboring screw aswell as the spacing of the flanks of the screw relative to one anothershould be selected such that a desired level of shear stress can beproduced in the case of a metallic material having dendritic propertiesthat is to be processed on the one hand, but whereby, on the other hand,the liquid phase of the metallic material cannot flow in uncontrolledmanner through the gap between the screw flanks, the head surfaces 4 andthe core surfaces 5 or between the head surfaces 4 and the inner walling6 of the extruder cylinder 2 due to its much lower viscosity. In thecase where the screws are driven in opposite senses, the meshing screwsform chambers that are progressively closed towards the front wherebythe material will be compulsorily transported therein.

[0059] The dendritic structures of the solid phase are converted intoglobulite particles by virtue of the shearing process on the one hand,whereby frictional heat is released on the other.

[0060] The driving assembly 8 for the screws 3 is located adjacent tothe region of the feed hopper 7 used for filling the extruder I withmetallic material, for example, in granular, chip-like or powder form.Furthermore thermal decoupling means (not shown) are arranged betweenthe driving assembly and the cylinder and screws.

[0061] Following the feed hopper 7, there are a series of feed devices 9to 12 via which additional materials can be fed into the extruder 1 atthose processing and temperature stages which are appropriate to thematerial being added. Thermal energy is introduced into the extruder 1from the exterior via heating collars 13 each of which is illustrated inhalf section.

[0062] The food devices 9 to 19 can be selected from amongst feedhoppers, metering screws, filler devices, belt or roving feeders,extruders (inclusive of the double screw extruder in accordance with theinvention) or injection aggregates for fluids.

[0063] An inert gas forming a protective gas is preferably applied tothe feed devices 9 to 12.

[0064] It should be emphasized at this point, that the screw 3 isillustrated only schematically and may have different configurationsalong its length. In particular, the corresponding screw sectionsopposite the feed devices 9 to 12 are matched to the respective functionof the screw.

[0065] The solid-liquid metallic thixotropic material produced in theextruder 1, which may be mixed with the most varied of additionalmaterials, is guided via a first heated channel 14 into the feed chamber15 of a die-casting cylinder 16. A differential piston 17 is disposedreversibly in the die-casting cylinder 16, said piston subdividing thecylinder chamber of the cylinder 16 into the feed chamber 15 and theinjection chamber 18. The piston surface 10 bounding the injectionchamber 18 is larger than the annular piston surface 20 bounding thefeed chamber 15. A means for preventing reverse flow in the form of anon-return valve 21 for example is located in the differential piston17. The means for preventing reverse flow 21 blocks the fluidicconnection in the form of a through passage (not shown) in thedifferential piston 17 from the injection chamber 18 to the feed chamber15, whilst it opens said through passage in the reverse direction.

[0066] A second heated channel 22 leading to the molding cavity 28 isadjacent to the injection chamber 18, said second channel being adaptedto be closed by an active controllable shut-off nozzle 23.

[0067] The differential piston 17 is displaceable in reversible mannerin the injection piston 16 by means of a hydraulic piston cylinder unit24 of a hydraulic system 25.

[0068] In operation, the thixotropic or even liquid metallic material,which is produced in the extruder 1 and which may be mixed with variousadditional materials, is guided via the first heated channel 14 into thefeed chamber 15 and then reaches the injection chamber 18 via thethrough passage in the differential piston 17, the outlet of saidinjection chamber being blocked by the shut-off nozzle 23. Due to thesurface ratio of the larger piston surface 19 relative to the smallerannular piston surface 20, the differential piston 17 is effectively adifferential pressure piston arrangement and automatically moves backuntil the quantity of material required for the subsequent injectionprocess has been loaded. The hydraulic piston-cylinder unit 24 iscontrolled during the filling process of the die-casting cylinder 16 insuch a manner that the differential piston 17 can be pushed back in acontrolled manner and will be stopped when the required quantity offilling material has been reached. The filling process takes place atthe low-pressure level produced by the extruder 1 (e.g. 5 to 120 bar).

[0069] In the succeeding injection process, the differential piston 17is pushed forward by the hydraulic piston cylinder unit 24, whereby thereverse flow blocking means 21 closes and the pressure in the injectionchamber 18 increases to the injection pressure (e.g. 1500-2000 bar). Thethixotropic or possibly liquid metallic material flows into the moldingcavity via the opened shut-off valve 23 and the second heated channel22. Leakage occurring at the high injection pressure plays no partbecause the leaked quantity can only enter the feed chamber 15 fromwhere it can be returned to the injection chamber 18. Sealing of thefeed chamber 15 relative to atmosphere or relative to a hydraulicchamber of the hydraulic piston-cylinder unit presents no problems dueto the substantially lower level of pressure.

[0070] Only one die-casting cylinder 16 is illustrated in the drawing ofFIG. 1 although two or more cylinders that are to be filled in parallelor alternately may be provided.

[0071] In this case, these cylinders may be supplied merely via thebranches of a first heated channel. The arrangement of multi-way valvesis not absolutely necessary thereby since the process of filling thedie-casting cylinders is effected on each occasion by means of thecontrol system for the appertaining hydraulic piston-cylinder unit.

[0072]FIG. 2 shows schematically a die-casting cylinder 30 forming analternative to that shown in FIG. 1 and which may be used together withthe double screw extruder 1 in accordance with the invention in the formof a component of a shaping appliance. The die-casting cylinder 30comprises a hollow cylinder 32 in which an injection piston 34 isreversibly guided.

[0073] In contrast to the die-casting cylinder described in connectionwith FIG. 1, the die-casting cylinder 30 of FIG. 2 does not haveseparate feed and injection chambers, but rather, these two chambers arecombined here into a chamber 38 in front of the piston surface 36.

[0074] In a first variant of the die-casting cylinder 30, the latterincludes a feed opening 40 which is arranged adjacent to the pistonsurface 36 in a withdrawn dead position of the piston 34. Here, thefood/injection chamber is filled from the side of the piston surface 36of the piston 34.

[0075] In a further variant, the feed opening 40′ is arranged at thefront end of the feed injection chamber 38 adjacent to a heated channel42 leading to the molding cavity. In this case, the chamber 38 can befilled for as long as the piston 34 remains in the withdrawn deadposition, or, whilst the piston 34 is moving from a frontal deadposition (dash—dotted illustration) into the withdrawn dead position(solid line illustration).

[0076] In a third variant, the feed opening 40″ is attached to theheated channel 42 leading to the molding cavity and is provided adjacentto the front end of the cylinder 32. The possible ways of filling thefeed/injection chamber 38 described in connection with the precedingvariants also apply in this case too.

[0077]FIG. 3 shows a cross-sectional view of the double screw extruder 1in accordance with the invention along the line 3—3 in FIG. 1. However,in the embodiment shown here, another heating device has been selectedinstead of the heating collars 13.

[0078] For simplicity, the two screws 3 are not illustrated in FIG. 3.They are arranged in the double cylinder hollow chamber 6 which offersenough space for two parallel, adjacently located, mutually meshingscrews 3.

[0079] Here, the cylinder 2 comprises transverse bores 44, 45 which aretransverse to the longitudinal direction thereof and are arrangedadjacent to the hollow chamber 6.

[0080] Heating cartridges 46, 47 are arranged in the cylindrical bores44, 45, whereby a very large heat flow to the materials being worked inthe extruder 1 can be produced by means of these cartridges due to theirproximity to the double cylinder hollow chamber 6.

[0081] After the heating cartridges 46, 47 have been inserted into thetransverse bores 44, 45, the latter are closed by means of an airtightplug 48, 49 of temperature insensitive material through which it ismerely necessary to insert electrical leads 50, 51. An insulating means52 can be applied externally to the cylinder 1 in a very simple manner,whereby said insulating means has the same thickness over the length ofthe cylinder 2 and external heating strips do not have to be taken intoconsideration hereby. The heating cartridges 46, 47 recur over thelength of the extruder cylinder 2 and permit individual heatingprocesses to take place over the length of the extruder 1 in the samemanner as the heating collars 13.

[0082] In an alternative, heating cartridges can be used in thetransverse bores which project above the periphery of the extrudercylinder so that the transition region of the heated cartridges islocated outside the cylinder and the heating region in the interior ofthe cylinder. In such a case, it is possible to dispense with thematerial droplets 48, 49. Dismantling of the arrangement and maintenancethereof are thereby simplified.

[0083] Due to the introduction of heat into the hollow chamber of theextruder in the vicinity thereof and the improved insulatingpossibilities, tie rods for the extruder can be provided externally ofthe insulating means 52 and these tie rods will experience far lowertemperatures then is the case for the usual extruders belonging to thestate of the art. These tie rods can thereby be produced from a moreeconomical material since they are subjected to much smallertemperature-induced stresses.

[0084] What is claimed as new and desired to be protected by LettersPatent is set forth in the appended claims:

What is claimed is:
 1. Apparatus for manufacturing semi-finishedproducts and molded articles from a metallic material, comprising: anextruder for producing a flow of the metallic material, and at least onedevice connected following the extruder for shaping the semi-finishedproducts and the molded articles, wherein the extruder has a screwsystem comprising at least two meshing screws.
 2. The apparatus of claim1, characterized in that the screws of the screw system are closelymeshing screws.
 3. The apparatus of claim 1, wherein the screws of thescrew system rotate in the same direction.
 4. The apparatus of claim 1,wherein the screws of the screw system rotate in opposite directions. 5.The apparatus of claim 1, further comprising one or more moldingcavities connected subsequent to the extruder and adapted to be loadedwith metallic material on a continuous or discontinuous basis.
 6. Theapparatus of claim 1, wherein the extruder further comprises feedconnections for side feeding of additional materials.
 7. The apparatusof claim 1, further comprising: one or more die-casting cylindersconnected subsequent to the extruder, one or more molding cavitiesconnected subsequent to the die-casting cylinders, one or more multi-wayswitches and heated channels connected between the extruder and thedie-casting cylinders, and between the die-casting cylinders and themolding cavities, respectively, wherein the multi-way switches andheated channels are used for controllably filling the die-castingcylinders with the flow of metallic material and for cyclically fillingpartial quantities of the metallic material into the molding cavities athigh pressure.
 8. The apparatus of claim 7, wherein the die-castingcylinder comprises an injection chamber, and the die-casting cylinder isfilled through the injection chamber.
 9. The apparatus of claim 8,wherein the die-casting cylinder comprises a piston and can be filledfor as long as the piston is in a withdrawn dead position.
 10. Theapparatus of claim 8, wherein the die-casting cylinder comprises apiston and can be filled whilst the piston is moved from a forward deadposition into a withdrawn position.
 11. The apparatus of claim 7,wherein the die-casting cylinder can be filled via the channel disposedbetween a die-casting cylinder and a molding cavity.
 12. The apparatusof claim 1, further comprising: one or more die-casting moldingcavities, one or more die-casting cylinders connected subsequent to theextruder, each die-casting cylinder having a cylinder chamber and aninjection piston in form of a differential piston which is disposed inthe cylinder chamber and subdivides the cylinder chamber into aninjection chamber and a feed chamber, and a fluidic connection disposedbetween the feed chamber and the injection chamber, said fluidicconnection incorporating a reverse flow preventing means which blocks afluid flow from the injection chamber to the feed chamber whileproviding continuity from the feed chamber to the injection chamber,wherein the feed chamber is in communication with an output port of theextruder via a heated channel and the injection chamber is incommunication with one or more of the die-casting molding cavities, andwherein a surface area of the differential piston bounding the injectionchamber is greater than a surface area of the differential pistonbounding the feed chamber.
 13. The apparatus of claim 12, wherein thesurface area of the differential piston bounding the feed chamber has anannular cross-section.
 14. The apparatus of claim 12, wherein acontrollable shut-off nozzle is arranged in the region between thedie-casting molding cavity and the injection chamber.
 15. The apparatusof claim 1, wherein the extruder comprises a cylinder wall and furtherincludes heating cartridges arranged in transverse bores in the cylinderwall for heating the extruder.
 16. The apparatus of claim 15, whereinthe extruder comprises an insulating layer arranged around the cylinderwall of the extruder and tie rods arranged externally of the insulatinglayer.
 17. Method of die-casting, continuous casting and extrusionmolding metallic materials using an extruder and shaping units connectedthereafter, comprising: providing an extruder with a screw systemcomprising two or more meshing screws, introducing a metallic materialinto the extruder, and controllably advancing the flow of the metallicmaterial in an extrusion direction towards the shaping units.
 18. Themethod of claim 17, further comprising feeding an additional material tothe extruder via a side-feeding appliance, and mixing the additionalmaterial with the metallic material in the extruder.
 19. The method ofclaim 18, wherein the side-feeding appliance is an extruder.
 20. Themethod of claim 18, wherein the additional material is selected from thegroup consisting of metallic alloying components, reinforcing fibers andadditives.
 21. The method of claim 17, wherein the metallic material isheated to a temperature between the solidus and the liquidus temperatureof the metallic material.
 22. The method of claim 17, wherein themetallic material is heated to a temperature which is approximately 5°C. to 10° C. above the liquidus temperature of the metallic material.